In the art relating to rotary gas and liquid fluid machines and especially relating to turbines and compressors for automotive engine turbochargers, it is considered that substantial improvements in engine efficiency and performance during transient operation could be made by reducing weight and inertia of the turbine and compressor rotors and by providing improved methods for sealing these rotors against the leakage of pressurized fluids past the rotating blades during operation.
In typical turbine and compressor designs, the weight of the assembly is related to size and weight of the blades and associated portions of the rotor, which are in turn functions of their size and shape and the strengths of the materials from which they are made. Sealing is generally accomplished by providing close clearances between the sides of the blades and the walls of the housing in which they operate. However, these clearances must be adequate to provide for manufacturing tolerances plus the dimensional variations occurring during operation of the unit at various temperatures, since rubbing of the blades on the housing would adversely affect efficiency, as well as causing undesired wear or damage. Where rubbing seals are utilized, their frictional contact will to some extent reduce operating efficiency of the machine.